Cigarette-attributable fires caused 10,130 deaths in the United States from 1990 to 1999. Recently-enacted laws in New York State (effective 28 June 2004) and Canada (effective 1 October 2005) regulate the ignition propensity of cigarettes, requiring that the majority of tested cigarettes self-extinguish when left unattended. The goal of the proposed study is to expand the science base on the regulation of cigarette fire risks through a program of transdisciplinary research that would rigorously evaluate the policy and its potential intended and unintended consequences. We propose five interrelated studies to investigate the effects of low ignition propensity (LIP) legislation on fire incidence, cigarette design, smoker behaviors, and toxin exposures. Aim 1 will examine the incidence of fires in NY, Massachusetts (MA), and Ontario (ON) before and after the implementations of LIP laws in NY and ON, allowing for both pre-post comparisons within sites, and contemporaneous comparisons between sites. Aim 2 will survey 1,800 smokers across the three sites above to determine their perceptions of their cigarettes, smoking behaviors, fire precautionary practices, experiences with cigarette-related fires, and beliefs about LIP laws. Aim 3 will examine the smoking topography and toxin exposures of 60 smokers each in NY, MA, and ON to determine if LIP cigarettes alter smoking behavior or exposure to smoke toxins (CO, NNAL, PAHs). Aim 4 will examine changes in cigarette design (blend, tobacco weight, circumference, ventilation, paper citrate, paper porosity, rod moisture) due to the LIP laws, and whether these changes significantly affect ignition propensity or thermal performance. Aim 5 will examine tobacco industry documents and patents on LIP cigarette designs, with the goal of developing a LIP cigarette documents and patents collection and examine trends in technology. Taken together, these studies comprise a comprehensive evaluation of the potential impacts of this harm-reduction policy, which will inform policymakers in other jurisdictions considering similar regulations.